Valve assemblies are commonly used in fuel injectors to control the flow of fuel through a nozzle outlet. One example of a valve assembly used in a fuel injector is a solenoid actuated valve assembly including a stator assembly, an armature, and a valve member. Typical solenoid actuated fuel injectors include a valve assembly that attaches the armature to a guide piece, which is coupled to the valve member. Due to movement of the guide piece under the influence of magnetic fields acting upon the armature via the stator assembly, the valve member moves between stops, such as a low-pressure seat and a high-pressure seat, which ultimately controls the flow of fuel passing through the nozzle outlet of the fuel injector. When the armature is coupled to the valve member, the valve assembly functions as a single unit, i.e., movement of the armature causes movement of the valve member, and vice versa. Coupling of the armature with the valve member throughout all modes of operation of the fuel injector may affect the performance of the fuel injector. For example, such coupling may hinder or compromise the various objectives of a solenoid actuated valve assembly, including maintaining the parallelism between the armature and the stator assembly, maintaining the perpendicularity of the guide piece to the stator assembly, minimizing side forces that may result in an imbalanced orientation and increased wear, minimizing the separation air gap between the armature and the stator assembly to maximize force, and enhancing the speed of armature travel.
Moreover, a coupled valve member has a valve travel distance equal to the armature travel distance, which may not always be desirable because the valve member only needs to travel a distance between the low-pressure seat and the high-pressure seat, while the armature needs to travel a greater distance between the initial air gap and the final air gap.
One example of a coupled valve member and an armature of a solenoid actuated valve assembly is provided in U.S. Pat. No. 7,347,383 (the '383 patent), which discloses an armature and a valve member that are connected together by a non-ferrous material in order to prevent any leakage of magnetic flux from the armature to the valve member. However, the '383 patent fails to address the problems associated with the physical coupling of the armature and the valve member such as the slower armature travel speeds, the inability to have different armature and valve member travel distances and travel speeds, and the difficulty of producing a single unit with ever-tighter tolerances so that the valve assembly can reduce variability when the armature is coupled to the valve member.
The present disclosure is directed to overcoming one or more of the problems set forth above.